Multitudes — a multitude of multitudes — of long-starved Washington sports fans inundated the city Tuesday in a spasm of the civic ecstasy that had become a faint memory for older residents and unknown to the young: hailing a champion in one of the big four professional sports.

An immense spring tide of red — Capitals jerseys, towels and signs — began to build before dawn, swamping a dozen blocks of Constitution Avenue NW in downtown Washington. By parade time, tens of thousands were jammed shoulder-to-shoulder, simply to be with their joyous, semi-sober hockey team, their well-traveled trophy and their disbelieving neighbors, a mass gathering of the giddy, Community with a Capital C amid a Capitals Sea.

On a sunny day that was still cool enough for the comfortable wearing of thousands of hockey jerseys purchased in recent days, the Washington Capitals capped a dizzying stretch of celebration that began the moment they clinched their first Stanley Cup and the city’s first major sports title in 26 years.

“Now we can celebrate all together and remember this moment for all our lives,” team captain Alex Ovechkin, who has sported the same gaptoothed grin for the past 108 or so hours, wrote on Instagram. “Time to party caps fans!!!!”

At the parade, Ovechkin hoisted the Cup to display to the delirious from atop an open-topped double-decker bus, two of which carried the team down the route with an escort of motorcycle police and kilt-wearing bagpipers. Some players nursed metal beer bottles as they waved, emitting and absorbing love decades in the making. Brooks Orpik held two, until he tossed one down to a pleading fan.

“It’s like holy water,” said lucky fan Hank Hebel, who is eight years above drinking age. “We’re baptized in the Cup.”

It was a day to be reborn, and to dress like a kid. With fans of all ages wearing the garb of their favorite players, the street was lined with baby Backstroms and octogenarian Oshies. The guy in the Philipp Grubauer jersey running down the street with the D.C. flag turned out to be Philipp Grubauer.

Mayor Muriel E. Bowser (D) wore No. 51 — plugging D.C. statehood — as she tossed parade trinkets from a preceding bus. Government entities from D.C. schools to the Pentagon took part in the planning (just as many of their hooky-playing employees took part in the crowd), with the roar of fighter jets and marching bands adding to the bone-shaking cheers along the way.

It was a Caps cacophony: a Dalmatian howled from the top of a Clydesdale-drawn beer wagon. Cars honked to the beat of an ambient “Let’s go Caps” chant, a Zamboni rumbled down a city street, and lightposts — like the ones that had been draped with screaming fans on game night — were now adorned with victory banners. The city was already in a state of euphoric emergency when D.C. police sent a mass alert to residents by cellphone that the parade had begun.

People snap photos as a bus carrying Washington Capitals players turns onto Seventh Street NW in downtown Washington during the raucous Stanley Cup celebration. (John McDonnell/The Washington Post)

Police and fire officials reported nothing but minor incidents during the parade and following rally on the Mall, a scene of teeming (teaming?) red. The stage, where players thanked their fans and heard the gratitude echo back a thousand-fold, was framed on one end by the dome of the Capitals’ Capitol and on the other by the big No. 1 of the Washington Monument.

“Check check,” said T.J. Oshie, one of several players to address the throng, after setting his beer next to the microphone. “Sorry about my voice. We’ve been partying in the streets for a couple of days.”

The throng roared yet again.

Metro said that more than 800,000 trips had been taken by 10 p.m. Tuesday as fans attended the celebrations. Managers reported no major problems, aside from a deer’s uneventful dash through a tunnel at the Crystal City station.

Metro General Manager Paul J. Wiedefeld, monitoring the flow at the Archives station Tuesday morning, hailed the “fantastic mood.”

The system ran on a rush-hour footing for most of the day to accommodate the crowds that poured from downtown stations in great red gushers. But many were in place before the first trains rolled. Justin Bryam, a 23-year-old from Frederick, Md., was ready to rock the red at the rally stage before dawn. Ready to expunge years of frustration with a full day of joy, he drove in Monday night, crashed with a family member, was in an Uber by 4:45 a.m. and arrived at the Mall about 5. And he wasn’t the first.

“It was still dark. Cold and dark,” he said, looking out at a crowd that had grown by thousands behind him. “To see this city come together and embrace hockey is just unbelievable to watch.”

The diligent shared space with the die-hards. Linsey Brown, 24, a newcomer from Utah, couldn’t get the day off, so she and a friend brought their laptops to telecommute from paradeside.

“We’re totally on the bandwagon,” she said above the din. “Success is all we know in D.C.”

Fans gather in their regalia along Constitution Avenue NW for the victory parade. (Matt McClain/The Washington Post)

Others blatantly blew through their morning calendars.

“I’ve got four meetings later, but I couldn’t miss this,” said commercial real estate broker Doug Damron, 42, his dark suit conspicuous amid the endless red. He was taking part less as a sports guy and more as a Washingtonian. “I’m not a huge hockey fan, but I’m a Washington, D.C., fan. And you have to be part of this. It’s historical.”

Whole swaths of springtime tourists were surprised to find themselves part of celebration that was more about the people of the city than its status as the seat of the federal government.

Annelie Enstjaerna, 50, and her family arrived from Stockholm on Friday and were taken aback by the size and exuberance of the capital city, transformed for now into the Capitals’ City.

“It’s very American,” Enstjaerna said, comparing the brash bacchanal shaking the corner of 17th Street and Constitution Avenue NW with the lower-key celebrations in Sweden. “This is huge.”

But no one in the crowd screamed louder, pumped fists higher or cried more openly than longtime fans. It was a day to expunge decades of frustration.

For many, Tuesday’s howl of streetside joy followed 44 years of breath-holding and five days of inhaling the unthinkable air of the big win. And blown away were all the near misses, all the carping, all the dissing of the DMV as the District of Choke, dismissed by ESPN commentator (and former Washington Post columnist) Michael Wilbon as “a minor league sports town.”

Nick and Erin Wesol, both 39, “had” to be here with their kids, Beckett, 8, and Quinn, 6. It was matter of tribe. “Everybody knew I was coming down here,” Nick said. “It doesn’t happen but probably once in a generation, especially around D.C.”

The Cup rolled down the avenue in a bubble of sustained bedlam. There it was atop the bus, seemingly undented from the journey it had taken from the glare of the Las Vegas Strip to the banks of the Potomac, a five-day cross-continental bachelor party through locker rooms and nightclubs and cookouts, passed from player to player, gulped from, rubbed glossy and clutched with desperate relief, the city’s new first citizen.

“Welcome to D.C., Stanley!” shouted a group of school-aged kids as it passed.

Amir Nasser, 10, is in his last week of fourth grade at Piney Branch Elementary school in ­Takoma Park. After staying up late to watch the team clinch, he wasn’t going to miss the first championship party of his lifetime, even if it was not an excused absence.

“I’m excited, but I haven’t really seen a sports parade so I don’t know how they do it,” he said.

He wasn’t alone in this city coming off a too-long drought of unalloyed sports triumph. But on Tuesday, it all came back.

Jacob Bogage, Rick Maese, Faiz Siddiqui, Ava Wallace, Adam Kilgore and Roman Stubbs contributed to this report.